It also concerns a system for generating chaotic sequences, an encrypting system, a method for measuring the orbit length of a discrete chaotic sequence and a computer program corresponding thereto.
More particularly, the invention relates to the field of secure data sharing, transmission and storage in data transmission networks.
The transfer of confidential data (company documents, medical information, research results, personal data of photo, video type, etc.) in an open environment using usual communication channels (cables, Internet, Mobile-radios, satellites, . . . ) must be performed with maximum security and at a sufficient transfer rate. For this purpose, crypto-systems based on chaotic signals are adequate for achieving the cited objectives. A determinant factor in any chaos-based cryptosystem is the generator of the chaotic sequences, which is used for the generation of secrete keys and for data enciphering/deciphering procedure in substitution and permutation operations. The confidentiality of data depends inter alia on the extent of the chaos (i.e. randomness) of the sequences produced by the chaotic sequence generator used.
However, chaotic signals have not been given wide use in state of the art encryption systems on account of their periodicity in cycles of fairly small finite lengths.
The document “Design and Analyses of Efficient Chaotic Generators for Crypto-Systems” by Safwan El Assad et al. in Advances in Electrical and Electronics Engineering IAENG Special Edition of the World Congress on Engineering and Computer Sciences 2008, Vol. 1, pages 3 to 12, describes a generator of integer value chaotic sequences particularly intended to form data encryption keys, the said generator comprising at least two discrete recursive filters at least of first-order generating an output chaotic sequence of integer values, each recursive filter comprising means to implement a nonlinear function connected via an exclusive-or gate to means for generating a perturbation sequence.